Topological susceptibility in two-flavor lattice QCD with exact chiral symmetry

Abstract

We determine the topological susceptibility ${\chi }_t$ in two-flavor QCD using the lattice simulations at a fixed topological sector. The topological charge density is unambiguously defined on the lattice using the overlap-Dirac operator which possesses exact chiral symmetry. Simulations are performed on a $16^3\times 32$ lattice at lattice spacing $\sim$ 0.12 fm at six sea quark masses $m_q$ ranging in $m_s/6$--$m_s$ with $m_s$ the physical strange quark mass. The ${\chi }_t$ is extracted from the constant behavior of the time-correlation of flavor-singlet pseudo-scalar meson two-point function at large distances, which arises from the finite size effect due to the fixed topology. In the small $m_q$ regime, our result of ${\chi }_t$ is proportional to $m_q$ as expected from chiral effective theory. Using the formula ${\chi }_t=m_q\Sigma /N_f$ by Leutwyler-Smilga, we obtain the chiral condensate in $N_f=2$ QCD as ${\Sigma }^{\overline{\mathrm{MS}}}(2GeV)=[252(5)(10)\mathrm{MeV}{]}^3$, in good agreement with our previous result obtained in the $\epsilon$-regime.

11 pages, 3 figures, v2: accepted for publication in PLB

References in corpus (4)

• Finite volume QCD at fixed topological charge
• Lattice gauge action suppressing near-zero modes of H_W
• Two-flavor lattice QCD simulation in the epsilon-regime with exact chiral symmetry
• Theta dependence of the vacuum energy in the SU(3) gauge theory from the lattice

Cited by in corpus (11)

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• Topological susceptibility in QCD with two flavors and 3-5 colors -- a pilot study
• Extracting hadron masses from fixed topology simulations
• New Insight about the Effective Restoration of U_A(1) Symmetry
• New insight on the quark condensate beyond chiral limit
• $U(1{)}_A$ axial anomaly, ${\eta }^{\prime }$, and topological susceptibility in the holographic soft-wall model
• Theta vacuum physics from QCD at fixed topology